Electrochemical Behavior of Anode-Respiring Bacteria on Doped Carbon Electrodes.

Cultivating anodic respiring bacteria (ARB) on anodes doped with metal-enhanced biological growth and affected higher electocatalytic activity (ECA). The anode doped with calcium sulfide (CaS) proved more favorable for ARB than the magnetite (Fe3O4) or iron(II) sulfide (FeS). Average anodic current densities of 8.4 Am2- (Fe3O4), 11.1 Am2- (FeS), and 22.0 Am2- (CaS) were achieved as compared to that of nondoped carbon (5.1 A m-2). Thus, CaS-doped graphite represents a promising anode material which is suitable for highly efficient bioelectrochemical systems (BES). Electrochemical evaluation during turnover and starvation using simple cycle voltammetry (CV) and derivative cycle voltammetry (DCV) indicated several extracellular electron transfer (EET) pathways characterized with lower potentials for biofilms. However, despite the high affinity of bacteria to iron, their lower ECA was kinetically attributed to the accumulation of self-produced mediators on iron-doped anodes.